A Model of Comet Outbursts Based on a Fragmentation of
                   Ice  Bodies in its Atmosphere

                  Andrienko D.A., Mishchishina I.I.

             Department of Astronomy, Kiev  University

An  outburst  of   comet  is  very   complicated  and    variable
phenomenon.  It is  the  reason   why  there   are  many   models
which  have  been suggested for an explanation of the  phenomena.
In this paper a   new model which is   based  on   a   suggestion
that  there   are   special  conditions  in  a  comet  head   and
requires  an  external  source  of energy is developed.

It   is   suggested   that   as   a   result  of destruction of a
comet  nuclear  surface  ice   bodies  are  ejected  into a comet
atmosphere and form a cloud.   The ice body  is  a mixture of   a
water    ice, a   mineral  and   an organic dust  and some gases.
The particles  are   unstable   and   have     irregular    form.
They    can     be sublimated   and destroied   yielding the gas,
the  dust   and the  particles themselves of   the smaller  size.
A  fragmentation of the ice bodies  can  be   stimulated both  by
a  heating in  the comet  atmosphere   and  by    an    affection
of   high    velocity corpuscula  stream particles  of the  solar
wind.  As   a result  of  the  fragmentation   process  a   total
surface   area   of     grains  increases.  This   leads  to   an
enhancement   of a   comet brightness  which accomplished  by  an
intensification of comet lines.

        A behavior  of the  cloud of  the ice  bodies is  described by
system  of  equations   based  on    conversation  laws.   Sublimation
and   fragmentation   in  the  cometary   atmosphere  are   taken
into  account  depending on   heliocentric distance comet  and initial
size of fragmentated particles.